Method of determining vanadium



AVERQPPM V Jan. 26, 1965 D. J- BROGAN METHOD OF DETERMINING VANADIUM Filed Nov. 8, 1961 RECOMMENDED A STM SAMPLE SIZE VANADIUM CONTENTMSTM) VS. SAMPLE SIZE BOMB" VA "'aoma" VALUE RECOMMENDED ASTM PPM v 36 EACH POINT REPRESENT AN AVERAGE 0F TEN DETERMINATIONS l 2 3 4 5 s 1 a 9 INVENTOR AVE. WEIGHT OIL SAMPLE (GMSJ Dmzze/ffiraym United States Patent 3,167,394 METHOD OF DETERMINING VANADIUM Daniel J. Brogan, 1649 N. 59th St., Philadelphia, Pa. Filed Nov. 8, 1961, Ser. No. 151,003 3 Claims. (Cl. 23-230) The present invention relates to methods of performing chemical analyses for vanadium present in combustible materials such as petroleum oils, fuel oil, organic materials, metallo-organic materials and the like.

A purpose of the invention is to greatly reduce the time and reduce the cost of determining vanadium in combustible materials.

A further purpose is to eliminate the danger from sulphuric acid in making vanadium analyses of combustible materials.

A further purpose is to avoid the necessity of running a pilot determination on the test material to establish the ASTM recommended sample size in analyzing for vanadium.

A further purpose is to expedite the programming for injection of additives to protect against vanadium in combustion equipment such as boilers, superheaters, reheaters and the like.

Further purposes appear in the specification and in i the claims.

The drawing illustrates the results of the tests employing the procedure of the invention and the comparison with the ASTM method.

The figure is a series of curves showing vanadium content by the ASTM method in parts per million plotted against sample size in grams and showing test results according to the present invention for reference purposes.

Describing in illustration but not in limitation and referring to the drawings:

Fuel oils are being used for combustion purposes to produce electrical energy and steam for heating which contain substantial quantities of vanadium which cannot be economically removed and which oils are attractively ,low in price. South American crude oil, such as residual from Venezuela, is an example. The vanadium is particularly harmful to boiler, superheater and reheater tubes since at the operating temperature it forms a liquid complex which is extremely corrosive to the metal of the tubes.

To prevent this corrosive attack, normal practice requires injecting a dry powder additive such as magnesium hydroxide into the combustion chamber to raise the melting point of the vanadium-containing complex so that it will not form a liquid at operating temperatures and will not be corrosive on the heat transfer tubes. The optimum rate of feed of additives depends on the vanadium content of the fuel oil, and the vanadium content varies widely with different oil samples. Accordingly, it is necessary to determine the vanadium content periodically to control the feed of additive in order to obtain proper corrosion protection. Where the quantity of additive is not properly regulated and proves to be excessive, difiiculty in heat transfer may result because of a deposit of additive on heat transfer surfaces.

The standard method for determining vanadium in fuel oils is that set forth in ASTM tentative specification D1548-59T, Vanadium in Navy Special Fuel Oil. This method requires of the order of 8 to 15 hours for each analysis, depending upon the size of the sample.

One of the problems presented by the ASTM method is the determination of the sample size, since the recommended sample size varies with the vanadium concentration in the sample. In dealing with a completely unknown sample, it is therefore necessary to make a pilot,

determination of the approximate vanadium content of "ice the sample in order to determine the recommended sample size to be used in the final determination. As explained later, if the sample size is larger than the recommended sample size, the results obtained by the ASTM method are likely to be appreciably low.

According to the ASTM method, the sample size equals F/C Where F is a sample factor depending upon the length of the light path through the solution and the dilution, and C is the expected vanadium concentration in ppm. Thus for a-given size of absorption cell and a given dilution, the sample size decreases as the vanadium content in ppm. increases.

According to the ASTM method, concentrated sulphuric acid is added to a small sample of fuel oil and the mixture is heated while stirring, until a sludge is formed and the sulphur oxides are driven off. This process involves some danger to the operator, and he must proceed very carefully and protect against burns of the skin and particularly the eyes. This step is eliminated in my method.

The residue is heated until it forms a dry coke.

This coke is then reduced to an inorganic ash in a mufile furnace held at a temperature not in excess of 550 C. This process must be performed slowly and carefully as it is essential to oxidize and drive off all carbonaceous material without volatilizing any of the vanadium itself. Care must be used so that too great an air flow into the muflle will not cause the ash to be blown from the beaker or to be lost because of too rapid burning of the carbonaceous material. Particular care should be taken to avoid contamination of the sample with particles from the roof, walls, and door of the furnace.

The ash is allowed to cool and then is treated with concentrated nitric and sulphuric acids and then heated carefully on a hot plate until most of the nitric acid fumes are driven off. The purpose of the nitric acid is to oxidize the vanadium completely. The purpose of the sulphuric acid is to keep the solution acid and act as an indicator to determine when most of the nitric acid fumes have been driven off, by the initial appearance of the white fumes of sulphur trioxide.

The final product is allowed to cool, carefully neutralized with sodium hydroxide, and sulphuric acid, phosphoric acid and sodium tungstate are added to produce a phosphotungstovanadic acid complex. The recommended concentration of sodium hydroxide is 50% by weight, and this procedure of neutralization involves danger of spattering, possible injury to the operator and possible loss of a portion of the sample. The intensity of the color is then measured in an absorption cell measuring either the absorbance or transmittance at 436 m or some other suitable wave length.

I have discovered that the speed and cost of the analysis can be greatly improved if both the combustion of the sample and also the oxidation of the vanadium are conducted in a combustion bomb. Combustion bombs are used in other types of analyses and give reliable results, for example, in the analysis of sulphur in coal, in which the sulphur content may be of the order of 300 times as great as the vanadium content in oil and therefore relatively easy to determine.

One of the great advantagse of the process of the invention is that the same sample size can be used and will give substantially accurate determinations of vanadium notwithstanding variation in the vanadium content. It is therefore possible to determine vanadium with high accuracy without making a pilot run to determine the recommended sample size.

In accordance with the invention, a suitable weighed sample of combustible material containing vanadium, for

is placed in the holder of a combustion'bomb. A conventional bomb calorimeter may be used of the type I which determines the'calorific value of coal. The bomb,

may be used with orwithout a liner. The liner may be of any'suitable material which will not'interfere with the test such as glass.

i example fuel oil, is placed in a capsule which in turn 1 The sample is ignited byanelectrical igniterf At the end Where no liner is employed, the bomb may suitably be made of a temperatureand oxygen resistant metalsuch as nickel or illium (see Metals Hand- I book, 1961, pages 1117, 1127 to 1 129), which will not interfere with the test.

Itis preferable to'add a small quantity of water to the .bomb before the reaction, to dissolve .the vanadium oxide .formed during the rection, and aid in removing;

' .H i Ort l :2) and 2.5 ml. of Na WO solution; The sodis the vanadium from the bomb.

Oxygen is admitted to the bomb until a suitable super- I atmospheric pressure of say30 atmospheres is reached,

It is preferable to provide ,for cooling the bomb gas .for

:example by placing the bomb in a water bath This can conveniently-be done. by using a calorimeter housing. The sample .is then ignited eleetricallyusingthe. usual bomb i gniter. The sample burns. in the enriched oxygen I atmosphere and the combustion of the sample is com- 'pleted within about 5 minutes. All of the vanadium present is oxidized to the highest valence. I

After the reaction or preferably during the reaction, the bomb is cooled as just described. An additional 5 minute period is allowed after completion of reaction to of -10 minutes remove, the bomb from the water bath, open, the' valve .and remove the excess oxygen slowly. Open the bomb,

Wash all interior surfaces of the ,bomb with distilled water and collect the washings, keeping the total of the washings, if convenient,.to a volume below ml. If the volume is in excess of 30 ml., evaporate to conform the sampleto a volume of 30 ml.

a Add to the washings 2 ml.-- of'H SO (1:1), 5 ml. of

uni tungstatef'solution contains 185 grams sodium tungstate, 'N.a WO 2I-I O per liter. Heat the solution to near boiling, cool to room temperature and quantitatively transa explained in the ASTM specification.

I also be obtained at 420 mu if a suitable calibration curve permit the combustion products to settle within the, I

bomb. .The excess of oxygen is .then discharged and the bomb is opened. All interior surfaces of'the bomb are rinsed with distilled water andthe washings are col-' lected. If the washings exceed approximately 30. ml. they are evaporated down to approximately 3() ,ml. I

The procedure for color development and determination is then carried out according to the ASTM method I obtain a correction factor forrthe bomb. This correction factor (scalereading on colorimeter) can bededucted from the vanadium sample readings. lfia-liner :of glass orother suitable inert materialis used in the bomb, it will minimize this error; It will of course be evident i values stated are recommended values which conform to .is.used. I I I I "It will'be evident-that'variationsin the quantities and also in the concentrations used are permissible and the ASTM practice, but may be varied.

oo'ivn Aars0 or ASTM METHOD: WITH ITHE :BOMB :METHOD OF THE PRESENT INVENTION '-In the ASTM procedure, different sample sizes are recommended for difie'rent concentrations of vanadium,

' ..and inanalyzing a'sample on-which no data is available,

it is necessary to run a pilot analysis to .determinethe I proper sample size to use in the ASTM analysis.

that as long'as the same compositionof reactants, the

same bomb andthe same composition of fuse; wire are employed, it will not be necessary to repeat the blank;

the same. I

Thus, the method of the invention-offersthe.advantage of great saving in time, reduction injexpense and avoidance of pilot determinations. Since time is ,saved,-it is possible to'obtain tighter. control; and have less time The drawing plots average ppm. of vanadium as ordinate" against average weight of sample ingrams for'three ditferentl-ots of oil. 1 Each point plotted on the curves represents the average of -10 determinations. Curve 20 at the top shows a point 21 illustrating the average vanadium determination by the ASTM method-using the ASTM I fiommended sample size, :while points 22 and 23'il lustrate that .the'iASTMjmethod gives substantially lower vanadium values if samples larger than the ASTM recommended size are used. The line;24 indicates the ASTM .ofthe'presentinvention, appliedto-the same sample of oil and correctediforthe blank. Considering now curve 26 for'an oil having a lower vention and of the ASTM Imethqdam apprqximately l vanad um content,;1n'th1s casethezrecommended ASTM sample-size' -iszj andthe actual sample tested according lag in additions of additive to protect against corrosion from the vanadium. I

EXAMPLE 1 I 7 Take an 0.8 to 1 gram sample of fuel oil and place in a silica or metal capsule in the holder of a conven-- Introduce oxygen-underpressure until a =pressure of atmospheres is reached.

It is of 99 11 9 -Understood thatthe'sizeof sample, the I .to vASTM practice gave vanadium values '28 which are almost the same-asthe value shown at 30for the bomb technique of the'present invention corrected for the blank.

A gai 'n, when, according to the "ASTM method larger samples were used, considerably lower vanadiumvalues were obtained asindicated at'31 and 32. I

C urve 33 for an oil which is considerably lower in I vanadium shows theASTM recommended sample size 34 and the vanadium content of this oil indicated at 35 for the ASTM recommended sample size, which again is about the-same .as the vanadiumvvalue 36 for this oil by the bombmethod of the present invention. corrected for the I blank. Once a'gainwhendarger samples were run with the ASTM method, ;lower vana'diumlvalues' as"indicated tion of vanadium is desirable, other techniques for deter- .In-ining vanadium may be used, such as the flame phothe same as the values obtained for vanadium using the Table 1C0nlinued ASTM recommended sample size, are secured by the SAMPLE METHOD present invention using the same sample size throughout. In the technique of the present invention, therefore, un-

104 .222 250 +0.4 like the ASTM procedure, it is no longer necessary to 114 25 vary sample size with vanadium content of the oils under 5 153% 18"; discussion or to make preliminary or pilot runs. 95 .202 249 0: 0

Table 1 shows the comparison of tests made for the 5 gig Zi -g 1%2 same three samples of oil by the ASTM method using 111 5 I237 251 Is substantially the recommended sample weight, and by the 3754 8? 5 :57; bomb method of the invention. In each case sample Aver. .8850 103 .220 249 weight, colorimeter scale reading at 420 mu, milligrams of vanadium per milliliter, ppm. of vanadium and per- SAMPLE #168810ASTM METEOD wntage deviation from the average are shown.

It will be evident that if desired the water used to wash -8-g out the bomb may be acidified to aid in keeping the 1 324 vanadium at the valence of 5 until the determination has 326 227 325 -0.6 b6 311 COIIlPlCtt-id. 22 34 +4 6 It will be seen that the percentage deviations are of the g2 g same order of magnitude when either of these test meth- 226 5 I e 386 317 -3.1 ods 1s us d. 280 327 It will be evident that while the colorimetric determinatometer' m... 267 301 -5. a In view of my invention and disclosure, variations and 272 314 -1.6 modifications to meet individual whim or particular need 318 I313 will doubtless become evident to others skilled in the art, .206 310 0.9 to obtain all or part of the benefits of my invention with- 233 $1; out copying the process shown, and I, therefore, claim all 290 342 +7.2 such insofar as they fall wtihin the reasonable spirit and $213 .265 319 scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. The method of quantitatively determining vanadium Table 1 in a sample of fuel oil, which comprises placing a sam ple of fuel oil in a combustion bomb, introducing a modi- SAMPLE #168090-ASTM METHOD 4L0 cum of water into the bomb, introducing oxygen under superatmospheric pressure in the bomb, igniting the sam- Percent ple in the bomb and burning the sample thereby conw gi gfi figggg W Rpm. V g g g gz verting all of the vanadium to a valence of 5 and dissolv- 420 my. From mg it in the water, cooling the bomb, dlscharglng excess Average r gas from the bomb, washing out the vanadium with water to dilute the solution of vanadium, adding to the solugg g 13% iii tion measured quantities of sulfuric acid, phosphoric acid 150.0 .320 142 +3.6 and sodium tungstate, heating to about boiling temperaigw ;I;gg a? if; ture, cooling to room temperature, conforming the solu- 152 .324 134 -2 tion to a quantitative volumetric volume, and determin- 132 .281 134 -2.2 50 157 1 147 +13 mg the vanadlum colonmetricaliy. 167 .350 135 1.5 2. The method of converting all of the vanadium in kl f 15g? ff a sample of fuel oil to a valence of 5, which comprises placing a sample of fuel oil containing vanadium in a SAMPLE #168696 BOMB-METH0D combustion bomb, introducing oxygen under superatmosphenc pressure to the bomb, igniting the content of 5M 132 the bomb, burning said fuel oil in the bomb, and deter- 111 137 mining the vanadium in the content colorimetrically. 50.0 140 +3.7 533 113 130 3. The method of converting all of the vanadium in 132 a sample of fuel oil to a solution containing all of said 56.2 +0.7 50 5m 122 135 vanadium at a valence of 5, which comprises placmg 2% $3 said sample of fuel oil containing vanadium in a combus- 0315 .135 137 +115 tion bomb, introducing a modicum of water to the bomb, 135 introducing oxygen under superatmospheric pressure to the bomb, igniting the content of the bomb, burning the SAMPLE #168875ASTM METHOD 60 oil in the bomb, rinsing the interior of the bomb with water, collecting the washings, and determining the vanafig 323 gig g:g dium in the washings colorimetrically. .8786 103. 5 .220 251 +0. 4

13g 8 0 References Cited by the Examiner 1955922221 11 3 5 egg 3:; :52 Hopps et 211.: Article in Analytical Chemistry, vol. 24 13332313333333333333 92' 11% 249 +014 (1 pages 1050-1051- Q .7398 87 .185 250 0. 0 iiti:-aa::::::::: 188 :iii 32% 13;? MORRIS WOLK, Pr mary Ex min r.

75 MICHAEL A. BRINDISI, Examiner. 

2. THE METHOD OF CONVERTING ALL OF THE VANADIUM IN A SAMPLE OF FUEL OIL TO A VALENCE OF 5, WHICH COMPRISES PLACING A SAMPLE OF FUEL OIL CONTAINING VANADIUM IN A COMBUSTION BOMB, INTRODUCING OXYGEN UNDER SUPERATMOSPHERIC PRESSURE TO THE BOMB, IGNITING THE CONTENT OF THE BOMB, BURNING SAID FUEL OIL IN THE BOMB, AND DETERMINING THE VANADIUM IN THE CONTENT COLORIMETRICALLY. 